Diplopia — common causes and referral priorities
Structured for Australian optometry practice.
Clinical decision support only
OptoGuide™ supports professional judgement and does not diagnose or replace clinician responsibility.
Quick answer
- First determine whether the diplopia is monocular or binocular, as this changes the likely site of pathology immediately.
- Binocular diplopia raises ocular motor, neurological, or orbital causes; monocular diplopia is more often optical or ocular surface related.
- Acute onset, ptosis, headache, pupil involvement, or neurological symptoms increase urgency.
- Refer urgently when a cranial nerve palsy, orbital process, or neurological cause is possible.
Common causes
- Decompensated phoria or longstanding binocular vision issue.
- Cranial nerve palsy.
- Orbital or thyroid eye disease.
- Refractive, corneal, or lens-related monocular diplopia.
- Neurological or vascular causes of new ocular misalignment.
Red flags (must not miss)
- Acute binocular diplopia with headache or neurological symptoms.
- Pupil involvement, ptosis, or painful eye movements.
- New limitation of ductions or incomitant deviation.
- Associated facial weakness, ataxia, or sensory symptoms.
- Orbital pain, proptosis, or lid swelling.
Use OptoGuide™ to guide this decision during consult.
What to check
- Monocular versus binocular status.
- Onset, variability, and associated neurological symptoms.
- Cover test, motility, and pattern of deviation.
- Pupil responses, lids, and cranial nerve-related signs.
- Anterior segment and media if monocular diplopia is suspected.
When to refer
- Same day if acute binocular diplopia is unexplained or neurologically suspicious.
- Urgent referral for cranial nerve palsy, orbital signs, or pupil-involving third nerve features.
- Routine referral when the picture is stable and consistent with non-acute binocular vision imbalance.
Initial management
- Classify monocular versus binocular diplopia before focusing on cause.
- Document ocular motility findings and any neurological association clearly.
- Escalate new acute binocular diplopia rather than observing without a clear explanation.
Clinical basis
This guidance reflects standard optometric clinical reasoning based on:
- Australian optometry clinical practice patterns
- Australian medicines regulation and PBS prescribing context
- Common ophthalmology referral standards
- Evidence-based clinical training and practice
Use OptoGuide™ during consult for structured clinical guidance.